Electrodialysis
Electrodialysis is a process that uses electric current to drive the separation of ions through a selective ion-exchange membrane. This technique is commonly used for the desalination of water, the concentration of ionic solutions, and the removal of ionic impurities from solutions.
Principle[edit | edit source]
The principle of electrodialysis is based on the movement of ions in an electric field. When an electric potential is applied across a series of ion-exchange membranes, cations (positively charged ions) migrate towards the cathode (negative electrode), and anions (negatively charged ions) migrate towards the anode (positive electrode). The ion-exchange membranes are selectively permeable, allowing either cations or anions to pass through while blocking the opposite charge.
Components[edit | edit source]
The main components of an electrodialysis system include:
- **Ion-exchange membranes**: These are typically made of polymers and are selectively permeable to either cations or anions.
- **Electrodes**: The anode and cathode are usually made of materials like platinum or graphite.
- **Spacer channels**: These are used to create flow paths for the solution and to support the membranes.
- **Power supply**: Provides the necessary electric potential to drive the ion migration.
Applications[edit | edit source]
Electrodialysis has a wide range of applications, including:
- **Desalination**: Used to remove salts from brackish water and seawater to produce fresh water.
- **Food and beverage industry**: Used for the demineralization of whey, juice concentration, and the removal of acids.
- **Chemical industry**: Employed in the recovery of valuable chemicals and the purification of process streams.
- **Pharmaceutical industry**: Used for the purification of drugs and the removal of ionic contaminants.
Advantages and Disadvantages[edit | edit source]
Advantages[edit | edit source]
- **Selective ion removal**: Can target specific ions for removal or concentration.
- **Energy efficiency**: Generally more energy-efficient than thermal desalination processes.
- **Scalability**: Can be scaled up or down to meet different production needs.
Disadvantages[edit | edit source]
- **Membrane fouling**: Membranes can become fouled by organic matter, scaling, or biofouling, which reduces efficiency.
- **High initial cost**: The cost of membranes and equipment can be high.
- **Limited to ionic species**: Non-ionic contaminants cannot be removed by electrodialysis.
See also[edit | edit source]
References[edit | edit source]
External links[edit | edit source]
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Contributors: Prab R. Tumpati, MD